1. Field of the Invention
The present invention relates generally to toilets, and more particularly, to toilets that can be used in vehicles, including recreational vehicles, boats, and the like.
2. Description of Related Art
One major benefit of modern recreation vehicles is that they are equipped with a complete bathroom facility which includes a flushing toilet, a shower with hot and cold water supply and a sink. These amenities can be used while the vehicle is disconnected from external water supply or sewer connection. RV's equipped with fixed toilets are also typically fitted with holding tanks that are mounted under the floor of the vehicle and located directly under the toilet. These toilets are commonly referred to as “gravity discharge” toilets, as shown in FIGS. 1 and 2. In some cases, where the vehicle is fitted with two bathrooms, one toilet is gravity discharge and mounted directly over the holding tank and the other is located remotely. Remote toilets transport waste from the toilet to the holding tank via a pump to flush water and waste or a vacuum transfer system that moves the flush water and waste via air pressure.
FIGS. 1 and 2 show an example where a toilet 110 is mounted directly above a holding tank 130. As shown, solid waste 104 and tissue tends to accumulate directly underneath a first opening 112 and second opening 114 of the toilet 110. The main source of odor from the holding tank 130 is the condition in which solid waste 104 and tissue accumulate directly under the openings 112, 114 of the toilet. Liquid waste 102 that enters the holding tank can fill the bottom area of the tank. The solid waste 104 accumulates in a pile or mound that can extend well above the top level of the liquid waste 102.
A deodorizing chemical may be added to the holding tank to reduce the odors that are emitted from the tank. However, these chemicals can contain strong biocides and sometimes emit an unpleasant odor from the chemical itself. Formaldehyde is a common active ingredient in these products. When deodorizers are added to the holding tank 130, the deodorizers run off the mound of solids and into the retained liquid. Thus, the waste above the liquid level 102 is extremely odiferous and is unaffected by the added deodorants. In addition, the presence of the mound of solid waste 104 can restrict the odors from reaching the exit vent.
These holding tanks are usually vented through a 1½-inch pipe that extends from the top of the tank through the roof of the trailer or motorhome. Gravity toilets have a mechanically operated valve positioned at a base 116 of the toilet bowl which opens during flushing allowing the flush water and waste to fall directly into the holding tank 130. A small amount of water is injected into the bowl while the valve is open to rinse the bowl surface. After the valve is closed, the flush water continues to briefly run into the bowl to leave a small amount above the flush valve to prevent waste odors from entering the living space of the vehicle. Waste passes from the second opening 114 and the base 116 to the holding tank 130 along a discharge tube 122. The discharge tube can be attached to a support surface 142, such as a floor, by an adapter 140 and seal 152. Further, a 3-inch sealing grommet 124 may be used to attach the discharge tube 122 to the holding tank 130.
The known toilet/holding tank system as described above emits very unpleasant odors when the toilet is flushed. Today there is a growing number of RV enthusiasts that spend upwards of 200 days each year living in their trailer or motorhome. Living in a confined space and having an unpleasant odor in the living area is a major discomfort to the occupants. They frequently add more deodorizing chemicals to the holding tank with no sustained relief from the problem. It is estimated that an average couple will spend between $150 to $250 per year for deodorizing chemicals.
Frequently, heavier than air malodors accumulate in the tank and are expelled into the bathroom when the toilet valve is opened. It is not uncommon for a negative pressure to exist inside the vehicle or trailer due to ventilation fans or cross winds over the exterior windows (if left open). Thus the malodors can be sucked into the living space the moment the toilet valve is opened.